#include <iostream>
#include <fstream>
#include <vector>
#include <deque>
#include <iomanip>
#define nmx 100005
using namespace std;
ifstream f ("darb.in");
ofstream g ("darb.out");
vector <int> v[nmx];
int n,a,b,vf[nmx];
void bfs (int source)
{
    vf[source]=1;
    deque <int> dq;
    dq.push_back(source);
    while (!dq.empty())
    {
        auto u=dq.front();
        dq.pop_front();
        for (auto it : v[u])
            if (!vf[it])
            {
                vf[it]=vf[u]+1;
                dq.push_back(it);
            }
    }
}
int main()
{
    f>>n;
    for (int i=1; i<=n; i++)
    {
        f>>a>>b;
        v[a].push_back(b);
        v[b].push_back(a);
    }
    bfs(1);
    int mx=0,st;
    for (int i=1; i<=n; vf[i]=0,i++)
        if (vf[i]>mx)
        {
            st=i;
            mx=vf[i];
        }
    bfs(st);
    mx=0;
    for (int i=1;i<=n;i++)
        mx=max(mx,vf[i]);
    g<<mx;
}